Hello,
Create a new node change the settings to the default you would like, and then go to the gear menu in the parameter dialogue and save the "Permanent Default". Do not worry this does not change how it "Permanently" it will save an .idx file in your personal preference. You can remove or move that .idx from your personal preference to anywhere in the $HOUDINI_PATH in order to distribute it through out your project. There are even are even more zanier ways to change the default preference, but that is the most robust and simple in most cases.
-Ben

I reworked my solution upon realizing that the ignore pivot attribute tickbox was still there. Much easier now, but let me know if for whatever reason it doesn't work for you. Kind of came at the problem in a very nonlinear fashion, so I may have missed some steps in trying to draft up a linear solution.

Generally speaking you should set system and other environment variables not related to Houdini in the shell, or to the system, before launching Houdini. You should not use Houdini.env for production use like that. I do not believe it will let you set non houdini environment variables. Plus there is no reading from the Houdini.env . Though that would be easy to test pretty quickly if something has changed.
Usually having a python like wrapper that injects all the variables into a shell prior to launching is the best. As you can use this same system on other DCC too.
Also side note, If you are messing with $HOME you should try and use $HOUDINI_USER_PREF_DIR instead. There are some known programs that do try and use $HOME, which is why SESI made the $HOUDINI_USER_PREF_DIR so you don't break other stuff.
Hope that helps

Ok now I'm trying to constrain the growth within a letter but also copy it over multiple scattered points on the letter. It seems to work fine except on the for each, it translates all primitives instead of having the 3 groups starting from the origin. I can't really visualize how I could achieve this, I tried to have the copy to points before the copy/transform but the scale is relative to the SOP centroid.
loopcopy to points.hipnc

You can add the SSS Samples Property to geometry objects:
Now when you render, you'll get more samples on the objects where you need it.
Pixel Samples are the one property that can only live at the object level; there are probably others, but that's the only one I can remember. Here's some documentation: http://www.sidefx.com/docs/houdini/props/_index
per_obj_sss.hipnc